The Bruins must find a way to contain Wildcats running back Ka'Deem Carey, as position in the Pac-12 South is on the line.

UCLA travels to Arizona on Saturday. The winner strengthens its position in the Pac-12 Conference South Division. Staff writer Chris Foster examines the story lines:

Carey carries the 'Cats

No. 16 UCLA has allowed only two running backs to top 100 yards this season. The Bruins lost both games.

Stanford's Tyler Gaffney battered UCLA for 171 yards in a 24-10 victory. Oregon's Byron Marshall went for 133 yards in a 42-14 victory.

It's no great revelation that when a team is successful on the ground, it often wins. That underscores UCLA's need to contain Arizona running back Ka'Deem Carey.

Carey averaged 148.4 yards per game to lead the nation in 2012. He is leading it again this season, averaging 153.1 yards.

"We have to be balanced, stay square and get this guy to the ground," said UCLA Coach Jim Mora. "That is not easy to do."

Last year, UCLA held Carey to 54 yards in a 66-10 victory. Mora attributed that in part to the Bruins getting an early lead. They were up, 21-0, after the first quarter.

A good offense could again be the best run defense. But the Bruins will have to deal with more than Carey. Quarterback B.J. Denker also has been an effective runner.

"He's elusive," said UCLA nose tackle Seali'I Epenesa. "We have to pressure him, but also try to keep him in the pocket."

Hits and misses

During the last four weeks, UCLA quarterback Brett Hundley has rolled up big numbers against lowly California and Colorado and been stifled by national powers Stanford and Oregon.

Arizona's is not the staunchest defense, but the Wildcats rank 15th nationally in passing efficiency defense and 27th in scoring defense.

The Bruins' young offensive line has developed some continuity. The return of Damien Thigpen should give the running game more life. Offensive coordinator Noel Mazzone loosened the reins a little last week, having the passing game go downfield more.

If Hundley is contemplating declaring for the NFL draft after this season, this would be a good game to show his wares.

History Lesson, Part I

Tucson has been to the Bruins what Tombstone was to the Clantons.

UCLA has lost the last four times at Arizona. The Wildcats' 48-12 rout two years ago was the most embarrassing. The teams brawled during the game, with 10 players being suspended by the conference.

Four of those players are expected to play Saturday: UCLA's Shaquelle Evans and Cassius Marsh and Arizona's Shaquille Richardson and Jourdon Grandon.

Mora addressed the issue with his team this week, though not specifically.

"I told them we have to do our best to play with great emotion and not ever become emotional," Mora said. "I didn't necessarily reference that game. I said this is what we need to do and this needs to be our mind-set and this is how we have to react. They knew what I was talking about."

History Lesson, Part II

The Bruins had a different kind of fight in them a year ago. They trounced Arizona at the Rose Bowl.

"There wasn't a single thing we did well," said Arizona Coach Rich Rodriguez. "You have to give them credit for that as well."

As to how that rout will affect his team in this game, Rodriguez said, "I would hope our players are competitive enough to be embarrassed by how they played."

Mora didn't put much stock in the redemption angle. "I think it can give you a little added motivation early in a game, maybe in your preparation," he said. "As the game goes on, that kind of dissipates and it turns back into football."

Barr code

The Pac-12 South is a four-team race. No. 22 Arizona State leads the division, with Arizona, UCLA and USC one game behind.

Arizona and UCLA still have Arizona State on the schedule. Arizona State plays at Utah on Saturday. USC is at California.

"This is about taking care of business," said UCLA linebacker Anthony Barr. "We have this week, then we get next week."